HISTO4 calculates histogram of multidimensional data samples 
   and supports data compression

 R = HISTO4(Y)
 R = HISTO4(Y, W)
	Y    data: on sample per row, each sample has with size(Y,2) elements 
	W    weights of each sample (default: [])
	     W = [] indicates that each sample has equal weight	
 	R is a struct with these fields: 
       R.X  are the bin-values 
       R.H  is the frequency of occurence of value X (weighted with W)
  	R.N  are the total number of samples (or sum of W)

 HISTO4 might be useful for data compression, because
 [R,tix] = histo4(Y) 
     	is the compression step
 R.X(tix,:) 
  	is the decompression step

 The effort (in memory and speed) for compression is O(n*log(n))
 The effort (in memory and speed) for decompression is only O(n)
 
 see also: HISTO, HISTO2, HISTO3, HISTO4

Package: nan